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Switch to mikuni BSR42

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Hi

After reading all of edison post I decided to switch my carb but I have some doubts and can't get an answer in the edison post, dont know why!

I am going to switch the stock carb for a mikuni BSR42 from a 2007 polaris outlaw 500 that is the same as a polaris predator 500,

This is my first doubt the outlaw and predator have the same carb correct?

Is this the best carb for a 97 XR400 with gordon mods, full stock running as a supermoto? Or should I go to the BST40?

The BSR should be easy to feet.

As the feeting part the problems I might find is the rear brake glass/switch. And may or may not have to make a extension to the carb to fit between the airbox and engine.

So far am I correct?

Another think I will need is the throttle from Motion Pro but the problem is that are three os them:

http://www.motionpro.com/motorcycle/search/by_motorcycle/all/2005/Polaris/Predator_500/Twist_Throttle_Kit/

Throttle Max Twist Rate

Vortex 95º 1.90

CR Pro 170º 2.93

CR Comp 190º 2.35

Is this information accurate? Witch one should I use, I ride her every day in the city and in the winter I do some enduro.

A thing I am not understanding is the choke, what do I need in this matter?

As far as jeting I think I know what to do, I will follow Perc's set up cause like him I ride at see level.

Am I missing any thing or any part? I would like to order everything from ebay at once.

I promise that if you help me now, and i can feet the carb, I will make a Topic just for this carb like the one that exists for the BST40SS

Thanks

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I don't get why anyone would want a Cv carb on an XR. I would just buy the XRs only 36mm pumper and stick it on and rage.

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I dont want to spend 400 dollares in a carb and in edison topic they say that there is no big difference, if there is one

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Oh, OK. So IS the carby you are wanting a CV? I will say those are great at NOT being picky about jetting and altitude changes. They aren't great for power.....but that may be why it is a 42mm instead of a 36.

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Thks I already knew that topic but dont know if its the same

I thnk they might be a little different but both are Cvs from quads.

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You want the Cr pro throttle Or the longest throw,the othes are too fast.I have some xr4s with pumpers,some with BSR42mm.The pumper little more strong low end.The 42mm more top end.I like hard tight trails,the 42 is cleaner down low,gives more hook up then pumper.The pumper I like better for high speed dirt roads,more wheel spin to slide around turns like a flat tracker.42 little more upper mid range and top end.Hope this helps you.BTR

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You want the Cr pro throttle Or the longest throw,the othes are too fast.I have some xr4s with pumpers,some with BSR42mm.The pumper little more strong low end.The 42mm more top end.I like hard tight trails,the 42 is cleaner down low,gives more hook up then pumper.The pumper I like better for high speed dirt roads,more wheel spin to slide around turns like a flat tracker.42 little more upper mid range and top end.Hope this helps you.BTR

Thanks, helps a lot. I dont want to spend the money in a pumper and to night I am ordering the BSR.

First I will try to adapt our throttle, let's see... If i cant I will order the cr pro

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Just bought the BSR42 from ebay. Waiting for is arrivel

First I will try to the adapt ours even if I have to make a homemade cable.

What was the problem you faced?

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The threaded section where it screws into the carb is different as is the end on the cable, the BSR42 uses a much smaller cable end than the stock carb. You might be able to adapt something but I don't like your chances.

Oh, OK. So IS the carby you are wanting a CV? I will say those are great at NOT being picky about jetting and altitude changes. They aren't great for power.....but that may be why it is a 42mm instead of a 36.

I thought fitting a CV carb to an enduro bike was a strange idea at first too, then I actually tried a BSR42 on my XR440 and I was pleasantly suprised. I'm definitely not lacking in top end power, I've got good usable power right up to 9000rpm and I've done just over 96mph with more to go before chickening out so I'm not short on horsepower either with the CV 👍

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I'm prepping to do the BSR42 conversion on my XR400.  I want to order the right twist kit the first time.  Do I order a Motion Pro Twist Kit CR Pro for a Polaris Predator 500?  Do any of you have the motion pro part number?  Thank you, I just hate to order the wrong one and wait for more parts.

 

JR

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I did this mod last year on my xr440 but have yet to dial in the tuning - it starts after a struggle - and runs well, but doesn't like to idle smoothly.

 

I'm currently running a 180 Main, 52.5 Pilot and am on the 3rd groove down on the needle. The bike seems to be running very lean (the plug, DPR8ea, is white) and the bike seems to be running hotter than usual. I've done the air box mod BUT have stuck with the oem exhaust and restrictor/baffle as I'm aiming to use this as along range tourer and didn't want to be too loud and attract attention in Central America. 

 

Anyone with a 440 mod and BSR 42 out there? I'd love some jetting advice.

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I'm prepping to do the BSR42 conversion on my XR400.  I want to order the right twist kit the first time.  Do I order a Motion Pro Twist Kit CR Pro for a Polaris Predator 500?  Do any of you have the motion pro part number?  Thank you, I just hate to order the wrong one and wait for more parts.

 

JR

Yes, you want the kit for the Predator 500.  Here's the kit from Motion Pro, part #01-0571

 

Also available at RMATV among others.

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I have a Honda 1985 XR350R and i put a Mikuni 36 mm Flat slide on the bike and wow what a difference. Got it from XR'S only in California. For $209.00

and it included the single cable throttle plus the housing, all I had to do was install a grip. Now this was some time ago years wise! Still got the bike and ride it all the time.

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I've been running the bsr42 on my 440 for a couple years now after reading the Edison thread.. I went this route because the pumpers were $$$ and lot of people reported tuning issues. I love it so far

 

I didn't rejet mine and ran with stock 2005 polaris 500 config. I did drill the main, I think to ~150 size, don't remember. I chose to run it on the richer side to keep the motor cooler. 180 seems pretty big. Have you tried taking the carb apart and thoroughly cleaning it? I didn't have to adjust anything, mine ran smooth as is.

 

You mentioned stock exhaust. I am running large headers and a conical muffler (fmf). Also "Baja trail rider" mentioned as well that the carb seems to run best with 400 AND exhaust.. I didn't really mess with my bsr42 much so I don't know it in n out like some of the others

 

I don't

I did this mod last year on my xr440 but have yet to dial in the tuning - it starts after a struggle - and runs well, but doesn't like to idle smoothly.

 

I'm currently running a 180 Main, 52.5 Pilot and am on the 3rd groove down on the needle. The bike seems to be running very lean (the plug, DPR8ea, is white) and the bike seems to be running hotter than usual. I've done the air box mod BUT have stuck with the oem exhaust and restrictor/baffle as I'm aiming to use this as along range tourer and didn't want to be too loud and attract attention in Central America. 

 

Anyone with a 440 mod and BSR 42 out there? I'd love some jetting advice.

 

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